1. Field of the Invention
The present invention relates to the internal combustion engine, and more particularly to the intake manifold of a compact V-type internal combustion engine such as would commonly be used in a lawn mower, snow blower, generator, or the like.
2. Description of Related Art
Internal combustion engines convert chemical energy to mechanical energy for a wide variety of applications. For example, a typical combustion engine converts heat into motive power by burning a mixture of air and a flammable hydrocarbon, such as gasoline, in a plurality of cylinders each of which has a moveable piston positioned therein.
An xe2x80x9cinternalxe2x80x9d combustion engine is so named because it describes an engine in which the fuel is burned within the engine itself. The fuel combines with oxygen in the air, and upon ignition thereof, become a gas. This gas expands to a volume that is hundreds of times as great as the liquid-form from which it came, and this volume increase occurs within a fraction of a second. The expansive force of the hot gas enables movement of the various working parts of the engine.
Most internal combustion engines are fueled using gasoline. For example, nearly all passenger automobiles and trucks are powered by gasoline engines, as are most lawn mowers, snow blowers, generators, tractors, small motorboats, motorcycles, motor-cross minibikes, all-terrain vehicles, and the like. These engines do not burn pure gasoline however, but instead burn a sprayed combination of the afore-mentioned mixture of air and gasoline.
The way in which this spray is formed varies among different types of engines. For example, raw fuel can be injected directly into the cylinders to form a ball of spray within each cylinder, or the air and fuel can be mixed within a carburetor that is upstream of the cylinders, by which the spray is then communicated to the cylinders by way of an intake manifold connected to a bank of cylinder heads. Regardless, when a spark plug within each cylinder xe2x80x9cfires,xe2x80x9d the gasoline undergoes its phase change to actuate the piston located within the cylinder.
Not uncommonly, the plurality of cylinders are arranged into two banks that are aligned in mutually inclined positions upon a common crankcase. An engine with such an arrangement of cylinders is commonly called a xe2x80x9cV-typexe2x80x9d internal combustion engine because the cylinders are arranged in a V-shaped configuration. Other cylinder arrangements are, of course, also known, such as engines having cylinders connected in-line and in other opposing states.
The number of cylinders in an internal combustion engine typically varies from one to twelve, although 16-cylinder engines have also been constructed. Engines that have a high number of large cylinders are commonly used in high power applications, while other internal combustion engines are compact, having only one or two small cylinders for use in low to moderate power applications, such as would commonly be found in a lawn mower, snow blower, generator, or the like. In a compact internal combustion engine, less room is available for the numerous working parts of the engine. Thus, designers of compact engines must recognize and solve unique problems that are not encountered with large engine applications.
Engines of all types and sizes generate tremendous amounts of heat due to the combustion process. This heat is frequently dissipated through a cooling system whereby the cylinders of the engine can be air cooled or liquid cooled. In a liquid cooled engine, the cooling system may comprise a coolant manifold that directs a coolant to a radiator assembly whereby the combustion heat can be dissipated by heat exchange with atmospheric air that is circulated by a rotating cooling fan. Such a radiator is commonly attached to the engine by various mounting brackets that are situated at various locations and in various configurations around the engine.
At relatively lower coolant temperatures, it is known to temporarily divert the engine coolant away from the radiator assembly. Bypassing the radiator assembly in this fashion is traditionally accomplished by positioning a thermostat in the cylinder heads and installing a flow control device downstream of the intake manifold. While satisfactory results can be thereby obtained, the competing demands for the limited space in a compact internal combustion engine often complicate successful use of traditional bypass mechanisms.
Briefly, the invention comprises an improved intake manifold for a compact internal combustion engine. The manifold comprises a pair of integrally formed arms that extend outward in substantially opposite directions from a centrally positioned carburetor flange. Air passageways are formed in each arm and terminate in a respective end thereof. The air passageways connect an air inlet that is formed at the carburetor flange to air outlets that are formed at the ends of the arms. In addition, a coolant chamber is integrally formed with the arms, and positioned between therebetween. Coolant passageways are formed in each arm and a coolant inlet is defined at the ends thereof. The coolant passageways connecting each coolant inlet to the coolant chamber, whereupon a first coolant path connects the coolant chamber to a radiator and a second coolant path connects the coolant chamber directly to a coolant pump. Finally, a thermostatic valve such as wax is disposed in the coolant chamber and operable to couple engine coolant received through the coolant passageways to either the first or second coolant path as a function of engine coolant temperature. Either separately or apart therefrom, the intake manifold can also comprise an integral radiator support element for attachment to a radiator assembly without the need for various mounting brackets situated throughout the engine.
As previously mentioned, small engine applications present unique challenges to the designers thereof. Particularly with respect to the compact internal combustion engine, it is desirable to get maximum usage out of a minimum number of components and in the limited space available. Accordingly, it is an object of the present invention to provide an intake manifold for a compact engine that maximizes functionality within a minimum of space. Significant cost and space savings inure to the multi-functional intake manifold, especially in this context of small engine applications. Still, it is yet another object of the present invention to provide an intake manifold that is less costly to manufacture and more functional as a whole.
The foregoing and other objects, advantages, and aspects of the present invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown, by way of illustration, a preferred embodiment of the present invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference must also be made to the claims herein for properly interpreting the scope of this invention.